Multiloop antenna arrays for high-frequency shipboard direction finding

The application of multiloop arrays to high-frequency direction finding in the complex reradiation environments of shipboard sites is analyzed in detail. Theoretical results show that the bearing error and blurring are reduced and multivalued calibration curves are eliminated as the number of loops in the array is increased. The coaxial spaced loop is shown to produce a 2 to 1 reduction in bearing error with respect to the simple loop and eliminates multivalued calibration curves for thin reradiators. The use of combination arrays such as
n
and
(n- 1)
or
n
and
(n- 3)
loops are shown to produce unambiguous direction finding patterns. The DF performance characteristics of a coaxial spaced loop plus simple loop array are demonstrated for a shipboard site. Comparison of simple loop and three loop array calibration curves verify the performance characteristics predicted by the theory.